2.2 Biological Molecules Flashcards
Describe the structure of a water molecule
- O δ- (attracts more electrons)
- H δ+ (O δ- makes H atoms slightly positive)
- Covalent bond
How is a Hydrogen bond formed in a water molecule?
There is a weak electrical attraction between a hydrogen molecule and an oxygen molecule. This happens because the δ- O bonds are attracted to the δ+ H bonds.
Describe the solvent properties of water
Solvent properties:
•Allows molecules and ions to be transported around living things whilst dissolved in water (as water is polar, the - and + parts are attracted to the + and - parts of the solvent)
•Molecules and ions can be transported around living things whilst dissolved in water
Describe the density+viscosity of water
- Ice is less dense than liquid water as when it goes from 4°C to freezing point the water molecules align themselves in a structure which is less dense (due to water’s polar nature)
- Bodies of water are therefore insulated against cold due to layer of ice on top reducing rate of heat list from rest of pond
- This provides an ideal habitat for living things as is water was less dense, aquatic organisms would find it very difficult to float
Describe the cohesion+surface tension of water
- This makes a drop of water appear spherical because of the H bonding pulling the molecules together
- This explains why water molecules move together
- Allows some insects to walk across water
- Columns of water in plant vascular tissue are pulled up the xylem tissue together from the roots.
Describe the heat and temperature of water
- Water temp is a measure of the kinetic energy of the water molecules
- The amount of Heat Energy required to increase the kinetic energy and temperature is known as the specific heat capacity
- Means that water does not change temp easily
- Living things need a stable temp for enzyme-controlled reactions to take place properly
- Aquatic organisms need a stable environments to live in
What are the 2 different types of glucose?
α-glucose (isomer of glucose)
C6H12O6
•component of glycogen+starch (which act as energy stores) + energy source
β-glucose (isomer of glucose)
C6H12O6
•energy source, component of cellulose (which provides structural support in plant cell walls
What are triglycerides used for?
- energy source + store
- thermal insulator
- buoyancy
- protection
- an example of a macromolecule
How is a triglyceride formed?
- condensation reaction
- H2O molecule is removed
- forms an ester bond.
- left with 3 fatty acid chains joined to glycerol. fatty acids contain carboxyl group. glycerol contains hydroxyl group.
Is a triglyceride saturated or unsaturated?
Unsaturated
What are lipids?
•Biological molecules made of O, C and H -fats, oils, cholesterol, steroids -Animals-fats -plants-oil •soluble in alcohol rather than water •not polar
Describe saturated and unsaturated fats
- Fatty acids can be saturated and unsaturated
- Saturated if the carbon atoms bond to many hydrogen atoms
- Unsaturated if one or more of the fatty acid chains contain C atoms which form a double bond with another C atom
- This means it can’t bond with as many H atoms, forming a “kink” in the chain
Describe glycogen
- energy store in humans
- large polysaccharide molecule
- joined by condensation reactions
- glycosidic bonds between c1-4
- branches between c1-6
Describe cellulose
- found in plants, makes up cell walls
- not starch
- made of β-glucose
- glycosidic bonds c1-4
- not branched straight line not spiralled
- not soluble
- H bonds hold structure in place, stop it spiralling + give strength + stabilise molecules
What are polysaccharides?
Polysaccharides can be made by joining many monosaccharides together.
What is a carbohydrate?
Carbohydrates are organic compounds which comprise of only C, H and O.
•energy source
•energy store
•structural unit
What are monosaccharides
- simplest “simple sugars”
- same no. of C and O atoms
- have the general formula CnH2nOn
- white crystalline solids
- dissolve in water to form sweet tasting solutions
What are disaccharides
Monosaccharides can be joined together to form disaccharides, which dissolve in water and also taste sweet
•condensation reactions
•α1-4 glucose bond formed by hydrolysis
What is amylose?
- starch
- polysaccharide
- monomer: α-glucose
- α1-4 glycosidic bonds
- H bonds hold the spiral in place
What is amylopectin?
- starch
- polysaccharide
- made of α-glucose
- α1-4 bonds
- α1-6 glycosidic branches
- spiral shape held in place by H bonds with branches emerging from the spiral
What are phospholipids?
•molecule consisting of glycerol, 2 fatty acids and one phosphate group
-macromolecules
What is cholesterol and steroids?
- cholesterol is steroid alcohol helps maintain fluidity of cell membranes
- made of 4 C rings
- it is also small and hydrophobic, found in the tails of phospholipids
- cholesterol used to make steroids. many steroids are hormones
What are proteins?
Proteins contain C, H, O and N. some contain Sulphur.
•either structural or functional/chemical
What do amino acids make up
Amino acids make up proteins
How are dipeptide bonds formed
Condensation reaction between 2 amino acids.
Forms a bond
What is the first structural level of a protein?
(All proteins)
Polypeptide chain
-chains of amino acids
-formed by peptide bonds
What is the second structural level of a protein?
(All proteins)
Secondary structure
-Alpha helices and Beta pleated sheets (1 polypeptide chain)
What is the third structural level of a protein?
(All protein)
Tertiary structure
-stabilised polypeptide chain (1 chain)
-bonds have formed, protein is functional
What is the fourth structural level of a protein?
(Some proteins)
Quaternary structure
-made of more than 1 polypeptide chain
Describe insulin
- binds to glycoproteins receptors on the outside of muscle and fat cells (done to increase uptake of glucose from blood + to increase rate of consumption of glucose) (helps to regulate blood sugar levels)
- globular protein
- specific amino acid sequence
- quaternary structure
- chemical
Describe collagen
- fibrous + structural
* found in tendons, ligaments
Describe elastin
- structural + fibrous
* found in skin, bladder
Describe keratin
- found wherever a body part needs to be hard + strong e.g nails, hair
- fibrous + structural
Describe haemoglobin
- found in red blood cells
- specific sequences (2 a chains + 2 b chains)
- quaternary structure
- space within chain (haem groups which attracts the O because it has a 2+ charge)
- conjugated as it contains an iron ion
- globular
Describe pepsin
- enzyme that digests proteins in the stomach
- globular
- chemical
- specific amino acid sequence
- not a conjugated protein
- tertiary structure
What is the ionic formula of nitrate
NO3-
What is the ionic formula of hydrogencarbonate
HCO3-
What is the ionic formula of phosphate
PO4 3-
What is the formula used when doing thin layer chromatography
Rf (ratio of distance moved by solute ) = distance from pencil line to centre of spot of pigment / distance from pencil line to solvent front
What kind of monosaccharide is ribose
Pentose monosaccharide
What is the difference between a hexose and a pentose monosaccharide
Hexose - 6 carbon atoms
Pentose - 5 carbon atoms
Glucose structure makes it
Structure makes it soluble so it can be easily transported. Chemical bonds contain a lot of energy.
Sucrose
Disaccharide Formed when a-glucose and fructose join together
Lactose
Disaccharide formed by joining B-glucose and galactose
What kind of monosaccharide is glucose
Hexose monosaccharide
Maltose
Disaccharide 2x a-glucose
